if N == 0 and X>=0 and X<=500 and Y<=500:
    pass
else: 
    if N > 0 and 0*N+X>=0 and 0*N+X<=500 and 20*N+Y<=500:
        pass 
    else:
        if N< 0 and 20*N+Y>=0 and 20*N+X<=500 and 20*N+Y<=500:
            pass
        else:
            print('Размер фигуры превышает максимальный размер поля')
            exit()